E-mail authentication is here, but has it arrived yet?

Nowadays, most e-mails may contain spam or phishing related data. Addressing the damage brought by such data, vendors came up with two primary authentication proposals: the Sender ID Framework (SIDF) and the Domain Keys Identified Mail (DKIM). SIDF lets the Internet service providers (ISPs) and businesses register their mail server's IP addresses with the Internet Corporation for Assigned Names and Numbers, which manages and coordinates the Domain Name System. The addresses are stored in DNS databases. On the other hand, DKIM is a cryptographic-based e-mail authentication approach that combines two digital-signature-based technologies, namely, the Yahoo-supported DomainKeys and the Cisco-supported Identified Internet Mail.